I've recently upgraded some old Burle B&W cameras to Samsung Techwin low-light colour ones. I re-used the old lenses off the Burles.
The problem I'm having is that while one of them is fine in every way, the other goes out of focus as darkness approaches. It's fine during the day but at night either in poor light or under floodlight, the image is blurred. I've been up and checked the focus ring, it's set to infinity as it's on a tall pole mount (fixed aspect) ..same as the good one. Image is correctly exposed.
The only difference I can see so far is that one camera has a Burle-branded lens (the good one) and the other has a Computar lens. They are both the same (fixed) focal length and are video-driven auto-iris.
Can anyone 'shed any light' on my dark focus problems? Might it be a back-adjustment problem where the infinity is only borderline focussed and the large aperture at night makes it worse?
